Holographic display

Abstract

A holographic display is provided. This holographic display comprises: a light source panel including a main laser source for generating a main laser beam, a plurality of light source pixels, each including a plurality of sub-laser sources for receiving the main laser beam and generating a sub-laser beam, and a waveguide for delivering the main laser beam of the main laser source to the plurality of sub-laser sources; a spatial light modulator disposed on the light source panel and including a plurality of light modulation pixels into which the sub-laser beams generated by the plurality of sub-laser sources are respectively incident; and a holography generation unit configured to provide hologram pattern information to the spatial light modulator.

Description

holographic display

[0001] The present invention relates to a holographic display.

[0002] As the information society develops, demand for display devices capable of displaying images is increasing in various forms. In particular, holographic displays utilize the principle of reproducing an image of an original object by diffracting a reference light onto a holographic pattern, which records the interference pattern created by interfering the object light reflected from the original object with a reference light.

[0003] Meanwhile, as a type of digital holographic display, research is actively being conducted on a holographic display that provides a computer-generated hologram (CGH) as an electrical signal to a spatial light modulator instead of directly exposing an original object to obtain a hologram pattern, and the spatial light modulator forms a hologram pattern according to the input CGH signal and diffracts a reference light to create a 3D image.

[0004] The problem that the present invention seeks to solve is to provide a thin holographic display.

[0005] Another problem that the present invention seeks to solve is to provide a holographic display capable of complex modulation.

[0006] The tasks of the present invention are not limited to the tasks mentioned above, and other technical tasks not mentioned will be clearly understood by those skilled in the art from the description below.

[0007] According to one embodiment of the present invention for solving the above problem, a holographic display includes a light source panel including a main laser generator for generating a main laser beam, a plurality of light source pixels each including a plurality of sub-laser generators for receiving the main laser beam and generating sub-laser beams, and a waveguide for transmitting the main laser beam of the main laser generator to the plurality of sub-laser generators, a spatial light modulator disposed on the light source panel and including a plurality of light modulation pixels onto which sub-laser beams generated from the plurality of sub-laser generators are respectively incident, and a holographic generation unit configured to provide hologram pattern information to the spatial light modulator.

[0008] The above sub-laser beam may be coherent light.

[0009] The above main laser beam can be incident on the sub laser generator to induce stimulated emission.

[0010] The waveguide includes a main waveguide and a sub waveguide, the main waveguide is connected to the main laser generator, and one end of the sub waveguide can be disposed adjacent to the main waveguide.

[0011] The main waveguide can provide the main laser beam provided from the main laser generator to the sub waveguide, and the sub waveguide can provide the main laser beam provided from the main waveguide to the sub laser generator.

[0012] The above main waveguide can be spaced apart from the above sub waveguide.

[0013] The above main waveguide can move the main laser beam located in the main waveguide to the sub waveguide by a coupling effect.

[0014] The coupling effect occurring between the main waveguide and the sub waveguide may be a direct coupling method.

[0015] The main waveguide provides the main laser beam to two or more of the sub-waveguides, the two or more sub-waveguides including a first sub-waveguide and a second sub-waveguide, the main waveguide including a first portion positioned before passing through the first sub-waveguide and the second sub-waveguide, and a second portion positioned after passing through the first sub-waveguide and before passing through the second sub-waveguide, and an energy intensity of the main laser beam within the second portion may be less than an energy intensity of the main laser beam within the first portion.

[0016] The energy intensities of the main laser beams incident on each of the first sub-waveguide and the second sub-waveguide may be the same.

[0017] The two or more sub-waveguides further include a third sub-waveguide, wherein the first sub-waveguide and the second sub-waveguide are spaced apart from the main waveguide, and the third sub-waveguide can be directly connected to the main waveguide.

[0018] The first to third sub-waveguides may be arranged sequentially along the path of movement of the main laser beam passing through the main waveguide.

[0019] The sub-waveguide provides the main laser beam to two or more of the sub-laser generators, the two or more sub-laser generators including a first sub-laser generator and a second sub-laser generator, the sub-waveguide including a first portion positioned before passing through the first sub-laser generator and the second sub-laser generator, and a second portion positioned after passing through the first sub-laser generator and before passing through the second sub-laser generator, and an energy intensity of the main laser beam within the second portion may be less than an energy intensity of the main laser beam within the first portion.

[0020] The energy intensities of the main laser beams incident on each of the first sub-laser generator and the second sub-laser generator may be the same.

[0021] The main waveguide includes a first main waveguide and a second main waveguide, and the waveguide further includes an initial waveguide positioned between the main waveguide and the main laser generator, and a splitter positioned between the initial waveguide and the main waveguide, wherein the splitter splits the main laser beam passing through the initial waveguide, and the split main laser beam can travel to the first main waveguide and the second main waveguide, respectively.

[0022] The above holographic display further includes a plurality of couplers arranged adjacent to each of the plurality of sub-laser generators, wherein the plurality of couplers can move the main laser beam located in the waveguide to each of the plurality of sub-laser generators by a coupling effect.

[0023] The coupler includes a diffractive optical element (DOE), and the coupler can diffract the main laser beam located in the waveguide to move the main laser beam to the sub-laser generator.

[0024] The coupling effect occurring between the above coupler and the above sub-laser generator may be an indirect coupling method.

[0025] The plurality of couplers include a first coupler and a second coupler, and the first coupler and the second coupler include a diffraction grating pattern including a convex portion and a concave portion, and the diffraction grating patterns of the first coupler and the second coupler may differ in at least one of a grating width, a pitch, a grating height, and a shape.

[0026] The start timing of applying the laser generation driving current applied to the main laser generator may be consistent with the start timing of applying the laser generation driving current applied to the sub laser generator.

[0027] The relative phase difference between the plurality of sub-laser beams generated from each of the plurality of sub-laser generators may be constant each time the laser generation driving current is applied.

[0028] According to one embodiment of the present invention, a holographic display can be made thinner.

[0029] According to a holographic display according to one embodiment of the present invention, complex modulation may be possible.

[0030] The effects according to the embodiments are not limited to those exemplified above, and more diverse effects are included in this specification.

[0031] FIG. 1 is a perspective view illustrating a holographic display according to one embodiment.

[0032] FIG. 2 is an exploded perspective view showing a holographic display according to one embodiment.

[0033] FIG. 3 is a cross-sectional view showing a holographic display according to one embodiment.

[0034] FIG. 4 is a cross-sectional view showing a light source panel and a spatial light modulator of a holographic display according to one embodiment.

[0035] FIG. 5 is a bottom view showing a light source panel according to one embodiment.

[0036] Figure 6 is an enlarged view of area A of Figure 5.

[0037] FIG. 7 is a schematic diagram showing a waveguide, a coupler, and a sub-laser generator according to one embodiment.

[0038] FIG. 8 is a cross-sectional view showing a coupler according to one embodiment taken along line X1-X1' of FIG. 7.

[0039] FIG. 9 is a cross-sectional view showing a coupler according to another embodiment taken along line X2-X2' of FIG. 7.

[0040] Fig. 10 is a cross-sectional view showing a coupler according to another embodiment.

[0041] Fig. 11 is a cross-sectional view showing a coupler according to another embodiment.

[0042] Fig. 12 is a cross-sectional view showing a coupler according to another embodiment.

[0043] FIG. 13a and FIG. 13b are timing diagrams showing the driving timing of each of the main laser generator and the sub laser generator according to one embodiment.

[0044] Fig. 14 is a plan view showing a spatial light modulator according to one embodiment.

[0045] Fig. 15 is a bottom view showing a light source panel according to another embodiment.

[0046] The advantages and features of the present invention, and the methods for achieving them, will become clearer with reference to the embodiments described in detail below together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms. These embodiments are provided solely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined solely by the scope of the claims.

[0047] When elements or layers are referred to as being "on" another element or layer, this includes both cases where the other element or layer is directly above the other element or layer or where there is another layer or material intervening therebetween. Similarly, references to "below," "left," and "right" include both cases where the other element or layer is directly adjacent to the other element or where there is another layer or material intervening therebetween. Like reference numerals throughout the specification refer to like elements.

[0048] Specific embodiments are described below with reference to the attached drawings.

[0049] FIG. 1 is a perspective view illustrating a holographic display according to one embodiment.

[0050] Referring to FIG. 1, a holographic display (10) according to one embodiment can reproduce an image of an original object by diffracting a reference light onto a holographic pattern that records an interference pattern obtained by interfering the object light reflected from the original object with the reference light. For example, the holographic display (10) can generate and reproduce a holographic image (HI) of a three-dimensional shape.

[0051] In some embodiments, the holographic display (10) can generate a holographic image (HI) using information about a digitized object via a computer instead of an actual original object. For example, a computer-generated hologram (CGH) generated by a holography generation unit (700) (see FIG. 2) is provided as an electrical signal to a spatial light modulator (300) (see FIG. 2), and the spatial light modulator (300) (see FIG. 2) can generate a holographic image (HI) by diffracting a reference light based on the computer-generated hologram (CGH).

[0052] The holographic image (HI) generated by the holographic display (10) according to the present embodiment is formed three-dimensionally in a three-dimensional space using interference of light, so that the user (PS) can view the holographic image (HI) with the naked eye without wearing separate glasses or a head mounted display (HMD).

[0053] Fig. 2 is an exploded perspective view showing a holographic display according to one embodiment. Fig. 3 is a cross-sectional view showing a holographic display according to one embodiment.

[0054] Referring to FIGS. 2 and 3, a holographic display (10) according to one embodiment may include a light source panel (100), a spatial light modulator (300), an optical member (500), and a holography generating unit (700).

[0055] The light source panel (100) can emit light in a direction facing the user (PS). For example, the light source panel (100) can emit light in a third direction (DR3).

[0056] In the illustrated drawing, the third direction (DR3) may refer to the thickness direction of the holographic display (10). The third direction (DR3) may be a vertical direction. The first direction (DR1) and the second direction (DR2) intersect with respect to the third direction (DR3), and may be, for example, a horizontal direction orthogonal to the third direction (DR3). The first direction (DR1) and the second direction (DR2) intersect with each other as a horizontal direction, and for example, the first direction (DR1) and the second direction (DR2) may be orthogonal to each other. Unless otherwise defined, in the present specification, the direction indicated by the arrows of the first to third directions (DR1, DR2, DR3) may be referred to as one side, and the opposite direction may be referred to as the other side.

[0057] The light source panel (100) may have a planar or plate-like shape extending in a direction perpendicular to the thickness direction of the holographic display (10). For example, the light source panel (100) may extend in a horizontal direction perpendicular to a third direction (DR3), for example, in the first direction (DR1) and the second direction (DR2). The thickness of the light source panel (100), for example, the length in the third direction (DR3), may be smaller than the horizontal length of the light source panel (100), for example, the length in the first direction (DR1) and the second direction (DR2).

[0058] The light source panel (100) may include a coherent light source. For example, the light source panel (100) may emit a coherent beam.

[0059] The light source panel (100) may include a plurality of light source pixels (SP) that are arranged to be spaced apart from each other in a horizontal direction (e.g., a first direction (DR1) and a second direction (DR2)). The plurality of light source pixels (SP) may each emit light in a third direction (DR3).

[0060] The light source panel (100) can individually control the intensity of light emitted from each of the plurality of light source pixels (SP). Accordingly, the light source panel (100) can individually control the amplitude of light emitted from each of the plurality of light source pixels (SP).

[0061] In some embodiments, the light source panel (100) may include at least one main laser generator (110) and a plurality of sub-laser generators (140).

[0062] The main laser generator (110) can generate a main laser beam (MLB). The main laser beam (MLB) can be divided through several optical members and incident on each of a plurality of sub-laser generators (140). The main laser beam (MLB) can be incident on each of the plurality of sub-laser generators (140) to induce stimulated emission in the active layers (143) (see FIG. 4) of the plurality of sub-laser generators (140).

[0063] A plurality of sub-laser generators (140) may be arranged for each of a plurality of light source pixels (SP). Each of the plurality of sub-laser generators (140) may generate a sub-laser beam (SLB). The sub-laser beams (SLB) may be incident on each of the light modulation pixels (MP) of the spatial light modulator (300).

[0064] A detailed description of the structure of the light source panel (100) will be described later with reference to FIG. 5, etc.

[0065] The spatial light modulator (300) may be disposed on one side of the light source panel (100). For example, the spatial light modulator (300) may be disposed on one side of the light source panel (100) in the third direction (DR3). The spatial light modulator (300) may be disposed on the display surface or the light-emitting surface of the light source panel (100). The surface of the light source panel (100) on which the spatial light modulator (300) is disposed may be a surface facing the user (PS). The spatial light modulator (300) may be located between the light source panel (100) and the user (PS).

[0066] The spatial light modulator (300) may have a planar or plate-like shape extending in a direction perpendicular to the thickness direction of the holographic display (10). For example, the spatial light modulator (300) may extend in a horizontal direction perpendicular to a third direction (DR3), for example, in the first direction (DR1) and the second direction (DR2). The thickness of the spatial light modulator (300), for example, the length in the third direction (DR3), may be smaller than the horizontal length of the spatial light modulator (300), for example, the length in the first direction (DR1) and the second direction (DR2).

[0067] The holographic display (10) according to the present embodiment can be easily made thinner by attaching a spatial light modulator (300) in a planar or plate-shaped shape to a light source panel (100) in a planar or plate-shaped shape.

[0068] The spatial light modulator (300) may include a plurality of light modulation pixels (MP) that are arranged to be spaced apart from each other in the horizontal direction. The plurality of light modulation pixels (MP) may transmit light emitted from the plurality of light source pixels (SP) in a third direction (DR3). The light emitted from the plurality of light source pixels (SP) may be transmitted through the plurality of light modulation pixels (MP) and provided to the user (PS). The user (PS) may recognize a holographic image (HI) through the light transmitted through the spatial light modulator (300).

[0069] The plurality of light modulation pixels (MP) of the spatial light modulator (300) can individually control the phase or amplitude of light emitted from the plurality of light source pixels (SP) of the light source panel (100). For example, the spatial light modulator (300) can individually control the phase or amplitude of light emitted from the plurality of light source pixels (SP) based on digital hologram pattern information provided from the holography generation unit (700), thereby generating a holographic image (HI).

[0070] The spatial light modulator (300) may be a transmissive spatial light modulator (300). For example, the spatial light modulator (300) may be a liquid crystal spatial light modulator (LC-SLM). However, the present invention is not limited thereto, and in another embodiment, the spatial light modulator (300) may be a reflective spatial light modulator (300).

[0071] The optical member (500) may be disposed on one side of the spatial light modulator (300). For example, the optical member (500) may be disposed on one side of the spatial light modulator (300) in the third direction (DR3). The optical member (500) may be disposed on the light-emitting surface of the spatial light modulator (300). The surface of the spatial light modulator (300) on which the optical member (500) is disposed may be a surface facing the user (PS). The optical member (500) may be positioned between the spatial light modulator (300) and the user (PS).

[0072] The optical member (500) can adjust the size and shape of the image, such as enlarging or reducing the image of the holographic image (HI), by controlling the modulated light (LGT) transmitted from the spatial light modulator (300). For example, the optical member (500) can include various lenses, such as a convex lens, a concave lens, a cylindrical lens, a compound lens, a Fresnel lens, an anamorphic lens, and a meniscus lens. However, the present invention is not limited thereto, and the optical member (500) may also include other members, such as a mirror.

[0073] The holographic generation unit (700) can generate a computer-generated hologram (CGH). For example, a computer-generated hologram is a holographic pattern and can include information about the amplitude and phase of light for generating a holographic image (HI).

[0074] The holography generation unit (700) can generate a hologram pattern by reflecting information about the amplitude and phase of the lights emitted from each of the plurality of light source pixels (SP) of the light source panel (100). The holography generation unit (700) can provide a hologram pattern in which information about the amplitude and phase of the lights emitted from each of the plurality of light source pixels (SP) of the light source panel (100) is reflected to the spatial light modulator (300). The spatial light modulator (300) can individually adjust the phase of the light according to the amplitude and phase of the lights reflected in the hologram pattern.

[0075] The holographic display (10) according to the present embodiment can constantly fix the relative phase difference of sub-laser beams (SLBs) generated from each sub-laser generator (140) by having the main laser beam (MLB) generated from the main laser generator (110) simultaneously induce stimulation emission from a plurality of sub-laser generators (140). This will be described later with reference to FIGS. 13a and 13b.

[0076] Since the relative phase difference of the sub-laser beams (SLBs) is fixed, the holography generation unit (700) can generate a hologram pattern by reflecting the fixed phase difference. The spatial light modulator (300) can control the phase of each sub-laser beam (SLB) by driving a plurality of light modulation pixels (MP) using the hologram pattern reflecting the fixed phase difference. Accordingly, each sub-laser beam (SLB) can be converted into modulated light (LGT) to form a holographic image (HI). The user (PS) can recognize the holographic image (HI) through the modulated light (LGT).

[0077] FIG. 4 is a cross-sectional view showing a light source panel and a spatial light modulator of a holographic display according to one embodiment.

[0078] Referring to FIG. 4, the light source panel (100) may include a main laser generator (110), a waveguide (120), a coupler (130), and a sub laser generator (140).

[0079] The main laser generator (110) can generate coherent light. For example, the main laser generator (110) can generate a main laser beam (MLB) as a type of laser beam.

[0080] A waveguide (120) may be connected to the main laser generator (110). The waveguide (120) may be a path for a laser beam to travel. For example, the main laser beam (MLB) may travel within the waveguide (120) by minimizing energy loss through repeated reflections (e.g., total internal reflections). In one embodiment, the waveguide (120) may be, but is not limited to, an optical fiber including a core and a clad.

[0081] A coupler (130) may be positioned adjacent to at least one side wall of the waveguide (120). The coupler (130) may be positioned between the waveguide (120) and the sub-laser generator (140). The coupler (130) may be arranged in a one-to-one correspondence with each of the plurality of light source pixels (SP). The coupler (130) may move at least a portion of the main laser beam (MLB) moving along the waveguide (120) to the sub-laser generator (140). In some embodiments, the coupler (130) may include a diffraction optical element (DOE). The coupler (130) may use diffraction of light to move the main laser beam (MLB) to the sub-laser generator (140).

[0082] The sub-laser generator (140) may be disposed on one side of the waveguide (120). In one embodiment, the sub-laser generator (140) may be physically separated from the waveguide (120). However, the present invention is not limited thereto, and the sub-laser generator (140) may be disposed to be in contact with the waveguide (120). The sub-laser generator (140) may be induced to emit stimulated light by a main laser beam (MLB) diffracted and transmitted by a coupler (130). The sub-laser generator (140) may emit a sub-laser beam (SLB) by the stimulated light emission.

[0083] In some embodiments, the sub-laser generator (140) may include a first electrode (141), a second electrode (142), and an active layer (143).

[0084] The first electrode (141) may be positioned adjacent to the waveguide (120). The first electrode (141) may be a transparent electrode or a semitransparent electrode. The first electrode (141) may allow the main laser beam (MLB) transmitted through the coupler (130) to pass through and reach the active layer (143). The first electrode (141) may allow light emitted from the active layer (143) to pass through and be incident on the light modulation pixel (MP) of the spatial light modulator (300).

[0085] The second electrode (142) may be positioned opposite the first electrode (141). The second electrode (142) may be positioned on the opposite side of the waveguide (120) with the first electrode (141) and the active layer (143) interposed therebetween. The second electrode (142) may be a reflective electrode. The second electrode (142) may reflect light generated from the active layer (143) toward the light-emitting surface where the first electrode (141) is positioned. The second electrode (142) may apply a different charge than the first electrode (141).

[0086] The active layer (143) may include an active medium in which repetitive stimulus emission can be induced. For example, the active layer (143) may include an active medium such as a solid, a liquid, a gas, or a semiconductor.

[0087] The active medium of the active layer (143) can be excited by the energy supplied by the main laser beam (MLB), and then spontaneously move to the ground state and emit light. The active medium of the active layer (143) can repeatedly stimulate and emit light by repeating the excited state and the ground state by the energy of the emitted light. The laser beam amplified by the repeated stimulated emission can be emitted to the outside of the sub-laser generator (140), and the laser beam emitted from the sub-laser generator (140) can be a sub-laser beam (SLB). After the sub-laser beam (SLB) is incident on the light modulation pixel (MP) of the spatial light modulator (300), the phase and / or amplitude can be modulated and emitted in the form of modulated light (LGT).

[0088] However, the structure of the sub-laser generator (140) is not limited to the structure illustrated in the drawing and described above. For example, the sub-laser generator (140) may include reflective electrodes that face each other and separate input / output structures. In this case, the light may be amplified by repeatedly induced stimulus emission within the active layer (143) by the reflective electrodes that face each other, and the amplified light may be emitted to the outside of the sub-laser generator (140) through the input / output structures. The structure of the sub-laser generator (140) may be modified in various ways.

[0089] FIG. 5 is a bottom view showing a light source panel according to one embodiment.

[0090] Referring to FIG. 5, the light source panel (100) may include a plurality of light source pixels (SP). The plurality of light source pixels (SP) may be arranged spaced apart from each other in a first direction (DR1) and a second direction (DR2). For example, as illustrated in the drawing, the plurality of light source pixels (SP) may be arranged in a matrix.

[0091] In the drawing, a plurality of light source pixels (SP) are depicted as being arranged in a first column (C1), a second column (C2), a third column (C3), a fourth column (C4), a fifth column (C5), or a sixth column (C6) and a first row (R1), a second row (R2), a third row (R3), or a fourth row (R4), respectively, but are not limited thereto. The number of the plurality of light source pixels (SP) and the number of columns and rows in which the plurality of light source pixels (SP) are arranged are not limited thereto.

[0092] The main laser generator (110) can generate coherent light. For example, the main laser generator (110) can generate a main laser beam (MLB) as a type of laser beam.

[0093] The waveguide (120) may be connected to a main laser generator (110). In some embodiments, the waveguide (120) may include an initial waveguide (121), a splitter (122), a main waveguide (123), and a sub-waveguide (124).

[0094] The initial waveguide (121) can be connected to the main laser generator (110). The initial waveguide (121) can extend in the second direction (DR2), but is not limited thereto. The initial waveguide (121) can connect between the main laser generator (110) and the main waveguide (123).

[0095] A splitter (122) may be placed between the initial waveguide (121) and the main waveguide (123). The splitter (122) may split the main laser beam (MLB) passing through the initial waveguide (121). The splitter (122) may be an optical member such as a lens or a mirror. The main laser beam (MLB) passing through the initial waveguide (121) may be split into at least two main laser beams (MLB) and may travel to the main waveguide (123). For example, as illustrated in the drawing, the main laser beam (MLB) split into two by the splitter (122) may each be incident on the main waveguide (123). In some embodiments, the energy intensity of the main laser beam (MLB) split into two by the splitter (122) may be approximately half the energy intensity of the main laser beam (MLB) located in the initial waveguide (121) before splitting.

[0096] In some embodiments, the initial waveguide (121) and splitter (122) may be omitted. In this case, the main waveguide (123) may be directly connected to the main laser generator (110).

[0097] The main waveguide (123) may be connected to the initial waveguide (121). The main waveguide (123) may extend in the first direction (DR1), but is not limited thereto. The main waveguide (123) may be arranged between the initial waveguide (121) and the sub waveguide (124). For example, the main waveguide (123) may be arranged between the initial waveguide (121) and the sub waveguide (124) in the second direction (DR2).

[0098] In some embodiments, the main waveguide (123) may include a first main waveguide (123a) and a second main waveguide (123b). The first main waveguide (123a) may be disposed on one side of the initial waveguide (121), and the second main waveguide (123b) may be disposed on the other side of the initial waveguide (121). The main laser beam (MLB) split by the splitter (122) may be incident separately on the first main waveguide (123a) and the second main waveguide (123b), respectively.

[0099] One end of the sub-waveguide (124) may be positioned adjacent to the main waveguide (123). The sub-waveguide (124) may extend in the second direction (DR2), but is not limited thereto. The sub-waveguide (124) may provide the main laser beam (MLB) incident from the main waveguide (123) to the sub-laser generator (140).

[0100] In some embodiments, the sub-waveguide (124) may include a first sub-waveguide (124a), a second sub-waveguide (124b), a third sub-waveguide (124c), a fourth sub-waveguide (124d), a fifth sub-waveguide (124e), and a sixth sub-waveguide (124f). However, the number of sub-waveguides (124) is not limited thereto.

[0101] The main laser beam (MLB) passing through the main waveguide (123) may be divided and incident on the first to sixth sub-waveguides (124a, 124b, 124c, 124d, 124e, 124f), respectively. For example, some of the main laser beam (MLB) traveling from the third column (C3) to the first column (C1) within the first main waveguide (123a) may be incident on the third sub-waveguide (124c), some may be incident on the second sub-waveguide (124b), and the remaining some may be incident on the first sub-waveguide (124a). Additionally, some of the main laser beam (MLB) traveling in the direction from the fourth column (C4) to the sixth column (C6) within the second main waveguide (123b) may be incident on the fourth sub-waveguide (124d), others may be incident on the fifth sub-waveguide (124e), and the remaining others may be incident on the sixth sub-waveguide (124f).

[0102] Accordingly, since energy is distributed from the main waveguide (123) to each sub-waveguide (124), the energy intensity of the main laser beam (MLB) may decrease as it moves toward the first column (C1) within the first main waveguide (123a), and the energy intensity of the main laser beam (MLB) may decrease as it moves toward the sixth column (C6) within the second main waveguide (123b).

[0103] That is, the first main waveguide (123a) may include a first portion positioned before reaching the third column (C3), a second portion positioned between the third column (C3) and the second column (C2), and a third portion positioned between the second column (C2) and the first column (C1), and the second main waveguide (123b) may include a first portion positioned before reaching the fourth column (C4), a second portion positioned between the fourth column (C4) and the fifth column (C5), and a third portion positioned between the fifth column (C5) and the sixth column (C6). At this time, the energy intensity of the main laser beam (MLB) in the first part of the first main waveguide (123a) may be greater than the energy intensity of the main laser beam (MLB) in the second part, and the energy intensity of the main laser beam (MLB) in the second part of the first main waveguide (123a) may be greater than the energy intensity of the main laser beam (MLB) in the third part. In addition, the energy intensity of the main laser beam (MLB) in the first part of the second main waveguide (123b) may be greater than the energy intensity of the main laser beam (MLB) in the second part, and the energy intensity of the main laser beam (MLB) in the second part of the second main waveguide (123b) may be greater than the energy intensity of the main laser beam (MLB) in the third part.

[0104] In some embodiments, the energy intensities of the main laser beams (MLBs) incident on the first to sixth sub-waveguides (124a, 124b, 124c, 124d, 124e, 124f) may be substantially equal to each other. The sum of the energy intensities of all main laser beams (MLBs) passing through the first to sixth sub-waveguides (124a, 124b, 124c, 124d, 124e, 124f) may be substantially equal to the total energy intensity of the main laser beams (MLBs) passing through the main waveguide (123).

[0105] The method for controlling the energy intensity of the main laser beam (MLB) incident from the main waveguide (123) to each sub-waveguide (124) will be described later with reference to FIG. 6.

[0106] The first sub-waveguide (124a) can extend in the second direction (DR2) to provide a main laser beam (MLB) to the sub-laser generators (140) arranged in the first column (C1). The second sub-waveguide (124b) can extend in the second direction (DR2) to provide a main laser beam (MLB) to the sub-laser generators (140) arranged in the second column (C2). The third sub-waveguide (124c) can extend in the second direction (DR2) to provide a main laser beam (MLB) to the sub-laser generators (140) arranged in the third column (C3). The fourth sub-waveguide (124d) can extend in the second direction (DR2) to provide a main laser beam (MLB) to the sub-laser generators (140) arranged in the fourth column (C4). The fifth sub-waveguide (124e) can extend in the second direction (DR2) to provide a main laser beam (MLB) to the sub-laser generators (140) arranged in the fifth column (C5). The sixth sub-waveguide (124f) can extend in the second direction (DR2) to provide a main laser beam (MLB) to the sub-laser generators (140) arranged in the sixth column (C6).

[0107] Accordingly, since the energy is distributed from the sub-waveguide (124) to each sub-laser generator (140), the energy intensity of the main laser beam (MLB) may decrease as it moves toward the fourth row (R4) within the first sub-waveguide (124a), the energy intensity of the main laser beam (MLB) may decrease as it moves toward the fourth row (R4) within the second sub-waveguide (124b), the energy intensity of the main laser beam (MLB) may decrease as it moves toward the fourth row (R4) within the third sub-waveguide (124c), the energy intensity of the main laser beam (MLB) may decrease as it moves toward the fourth row (R4) within the fourth sub-waveguide (124d), the energy intensity of the main laser beam (MLB) may decrease as it moves toward the fourth row (R4) within the fifth sub-waveguide (124e), and the energy intensity of the main laser beam (MLB) may decrease as it moves toward the fourth row (R4) within the sixth sub-waveguide (124f). As one moves in the row (R4) direction, the energy intensity of the main laser beam (MLB) may decrease.

[0108] That is, the sub-waveguide (124) may include a first portion located before reaching the first row (R1), a second portion located between the first row (R1) and the second row (R2), a third portion located between the second row (R2) and the third row (R3), and a fourth portion located between the third row (R3) and the fourth row (R4). At this time, the energy intensity of the main laser beam (MLB) in the first portion may be greater than the energy intensity of the main laser beam (MLB) in the second portion, the energy intensity of the main laser beam (MLB) in the second portion may be greater than the energy intensity of the main laser beam (MLB) in the third portion, and the energy intensity of the main laser beam (MLB) in the third portion may be greater than the energy intensity of the main laser beam (MLB) in the fourth portion.

[0109] In some embodiments, the energy intensities of the main laser beam (MLB) incident on each sub-laser generator (140) from each sub-waveguide (124) may be substantially equal to each other.

[0110] For example, the energy intensity of the main laser beam (MLB) incident on the sub-laser generator (140) arranged in the first row (R1) from the first sub-waveguide (124a), the energy intensity of the main laser beam (MLB) incident on the sub-laser generator (140) arranged in the second row (R2) from the first sub-waveguide (124a), the energy intensity of the main laser beam (MLB) incident on the sub-laser generator (140) arranged in the third row (R3) from the first sub-waveguide (124a), and the energy intensity of the main laser beam (MLB) incident on the sub-laser generator (140) arranged in the fourth row (R4) from the first sub-waveguide (124a) may be the same as each other.

[0111] Likewise, the energy intensities of the main laser beams (MLB) incident on each of the sub-laser generators (140) arranged in the first to fourth rows (R1, R2, R3, R4) in each of the second to sixth sub-waveguides (124b, 124c, 124d, 124e, 124f) may be the same. Accordingly, the main laser beams (MLB) having the same energy may be incident on each of the sub-laser generators (140) arranged in a matrix.

[0112] In some embodiments, the sum of the energy intensities of the main laser beams (MLBs) incident on the entire sub-laser generator (140) may be substantially equal to the sum of the energy intensities of the entire main laser beams (MLBs) passing through the first to sixth sub-waveguides (124a, 124b, 124c, 124d, 124e, 124f).

[0113] The coupler (130) may be arranged in a one-to-one correspondence with each of a plurality of light source pixels (SP). The coupler (130) may be arranged in a one-to-one correspondence with each of a plurality of sub-laser generators (140). The energy intensity of the main laser beam (MLB) incident from the sub-waveguide (124) to the sub-laser generator (140) may be controlled by the coupler (130). The method by which the coupler (130) controls the energy intensity of the main laser beam (MLB) incident from the sub-waveguide (124) to each sub-laser generator (140) will be described later with reference to FIG. 7.

[0114] Figure 6 is an enlarged view of area A of Figure 5.

[0115] In addition to FIG. 5, referring to FIG. 6, at least a portion of the main laser beam (MLB) passing through the main waveguide (123) may travel to the sub-waveguide (124) by a coupling effect. In some embodiments, the main laser beam (MLB) may travel from the main waveguide (123) to the sub-waveguide (124) by a direct coupling method. The direct coupling method refers to a method in which the laser beam travels directly between two waveguides without a transmission medium.

[0116] The main waveguide (123) may be spaced apart from the sub-waveguide (124) by a specific gap (G0). The waveguide (120) may include a coupling region, which is a region where a coupling effect occurs between the main waveguide (123) and the sub-waveguide (124). The length of the coupling region may be defined as a coupling length (L0).

[0117] When the separation distance between the main waveguide (123) and the sub waveguide (124) is defined as G0 and the length of the coupling region where the coupling effect occurs between the main waveguide (123) and the sub waveguide (124) is defined as L0, the energy intensity E of the main laser beam (MLB) moving from the main waveguide (123) to the sub waveguide (124) can satisfy the following mathematical expressions 1 and 2.

[0118] [Mathematical Formula 1]

[0119]

[0120] [Equation 2]

[0121]

[0122] The energy intensity E of the main laser beam (MLB) moving from the main waveguide (123) to the sub-waveguide (124) may be proportional to the square of the sine function of (β*L0). Here, β may be proportional to an exponential function of a negative multiple of G0. α, γ, and δ may be coupling coefficients, and may be coefficients determined according to the wavelength of light moving through the main waveguide (123) and the sub-waveguide (124), the refractive index inside the main waveguide (123) and the sub-waveguide (124), etc.

[0123] The holographic display (10) according to the present embodiment can control the energy intensity of the main laser beam (MLB) moving from the main waveguide (123) to each sub-waveguide (124) by controlling the size of the gap (G0) and the size of the coupling length (L0). Accordingly, main laser beams (MLB) having the same or different energy intensities can be applied to the first to sixth sub-waveguides (124a, 124b, 124c, 124d, 124e, 124f).

[0124] In one embodiment, as described above, since energy is distributed from the main waveguide (123) to each sub-waveguide (124), the energy intensity of the main laser beam (MLB) may decrease as it moves in the direction of the sixth column (C6) within the second main waveguide (123b). Accordingly, when applying the main laser beam (MLB) with the same energy size to the first to sixth sub-waveguides (124a, 124b, 124c, 124d, 124e, 124f), the first gap (G1) between the second main waveguide (123b) and the fourth sub-waveguide (124d), the second gap (G2) between the second main waveguide (123b) and the fifth sub-waveguide (124e), and the third gap (G3) between the second main waveguide (123b) and the sixth sub-waveguide (124f) may be different from each other.

[0125] Although the first gap (G1) is illustrated as being larger than the second gap (G2) and the second gap (G2) is larger than the third gap (G3) in the drawing, this is not limited thereto. For example, the first gap (G1) may be smaller than the second gap (G2), and the second gap (G2) may be smaller than the third gap (G3). As another example, the second gap (G2) may be larger than or equal to the first gap (G1) and the third gap (G3). As another example, when the coupling length (L0) is adjusted, the sizes of the first gap (G1), the second gap (G2), and the third gap (G3) may all be the same. The sizes of the first gap (G1), the second gap (G2), and the third gap (G3) may be variously modified depending on the energy size of the main laser beam (MLB) to be applied to each sub-waveguide (124).

[0126] In another embodiment, when applying the main laser beam (MLB) with the same energy size to the first to sixth sub-waveguides (124a, 124b, 124c, 124d, 124e, 124f), the first coupling length (L1) between the second main waveguide (123b) and the fourth sub-waveguide (124d), the second coupling length (L2) between the second main waveguide (123b) and the fifth sub-waveguide (124e), and the third coupling length (L3) between the second main waveguide (123b) and the sixth sub-waveguide (124f) may be different from each other.

[0127] However, the present invention is not limited thereto, and when adjusting the gap (G0), the sizes of the first coupling length (L1), the second coupling length (L2), and the third coupling length (L3) may be the same. Similarly to the first gap (G1), the second gap (G2), and the third gap (G3), the sizes of the first coupling length (L1), the second coupling length (L2), and the third coupling length (L3) may be variously modified depending on the energy size of the main laser beam (MLB) to be applied to each sub-waveguide (124).

[0128] Fig. 7 is a schematic diagram showing a waveguide, a coupler, and a sub-laser generator according to one embodiment. Fig. 8 is a cross-sectional view showing a coupler according to one embodiment taken along line X1-X1' of Fig. 7. Fig. 9 is a cross-sectional view showing a coupler according to another embodiment taken along line X2-X2' of Fig. 7. Fig. 10 is a cross-sectional view showing a coupler according to yet another embodiment. Fig. 11 is a cross-sectional view showing a coupler according to yet another embodiment. Fig. 12 is a cross-sectional view showing a coupler according to yet another embodiment.

[0129] In addition to FIG. 5, referring to FIGS. 7 to 12, at least a portion of the main laser beam (MLB) passing through the sub-waveguide (124) may travel to the sub-laser generator (140) by a coupling effect. In some embodiments, the main laser beam (MLB) may travel from the sub-waveguide (124) to the sub-laser generator (140) by an indirect coupling method. The indirect coupling method refers to a method in which a laser beam travels between two waveguides through a transmission medium. In the light source panel (100) according to the present embodiment, the transmission medium of the indirect coupling may be a coupler (130).

[0130] The sub-waveguide (124) may be spaced apart from the sub-laser generator (140). However, this is not limited to the above, and the sub-waveguide (124) and the sub-laser generator (140) may be in contact with each other, but the optical path may be blocked.

[0131] A coupler (130) may be placed between the sub-waveguide (124) and the sub-laser generator (140). The main laser beam (MLB) passing through the sub-waveguide (124) may travel to the sub-laser generator (140) through the coupler (130). For example, the main laser beam (MLB) passing through the sub-waveguide (124) may be diffracted by the coupler (130) and travel to the sub-laser generator (140).

[0132] In some embodiments, the coupler (130) may include a diffraction optical element (DOE). For example, as illustrated in FIGS. 8 and 9 , the coupler (130) may include a diffraction grating pattern including convex portions (131) and concave portions (132).

[0133] The holographic display (10) according to the present embodiment can control the energy intensity of the main laser beam (MLB) moving from the sub-waveguide (124) to each sub-laser generator (140) by controlling the grating width, pitch, grating height, shape, etc. of the diffraction grating pattern. Accordingly, the main laser beam (MLB) having the same or different energy intensity can be applied to each sub-laser generator (140).

[0134] For example, as described above, since energy is distributed from the sub-waveguide (124) to each sub-laser generator (140), the energy intensity of the main laser beam (MLB) may decrease as it moves toward the fourth row (R4) within the sub-waveguide (124). Therefore, when the main laser beam (MLB) is to be applied to each sub-laser generator (140) with the same energy size, the grating width, pitch, grating height, shape, etc. of the diffraction grating pattern may be different. Alternatively, even when the main laser beam (MLB) is to be applied to each sub-laser generator (140) with different energy sizes rather than the same energy size, the energy size of the main laser beam (MLB) applied to the sub-laser generator (140) may be controlled by adjusting the grating width, pitch, grating height, shape, etc. of the diffraction grating pattern.

[0135] In one embodiment, as illustrated in FIG. 7, the sub-laser generator (140) located in the first row (R1) can be provided with the main laser beam (MLB) diffracted by the first coupler (130_1). The sub-laser generator (140) located in the second row (R2) can be provided with the main laser beam (MLB) diffracted by the second coupler (130_2).

[0136] As illustrated in FIGS. 8 and 9, the first coupler (130_1) and the second coupler (130_2) may have different grating widths, pitches, and grating heights of the diffraction grating patterns. The grating width of the diffraction grating pattern may be defined as the width of the convex portions (131), the pitch may be defined as the sum of the widths of the adjacent convex portions (131) and the widths of the concave portions (132), and the grating height may be defined as the height of the convex portions.

[0137] For example, the grating width (W1) of the diffraction grating pattern of the first coupler (130_1) may be larger than the grating width (W2) of the diffraction grating pattern of the second coupler (130_2). The pitch (P1) of the diffraction grating pattern of the first coupler (130_1) may be larger than the pitch (P2) of the diffraction grating pattern of the second coupler (130_2). The grating height (H1) of the diffraction grating pattern of the first coupler (130_1) may be larger than the grating height (H2) of the diffraction grating pattern of the second coupler (130_2).

[0138] However, it is not limited thereto, and the grating width (W1) of the diffraction grating pattern of the first coupler (130_1) may be smaller than the grating width (W2) of the diffraction grating pattern of the second coupler (130_2), the pitch (P1) of the diffraction grating pattern of the first coupler (130_1) may be smaller than the pitch (P2) of the diffraction grating pattern of the second coupler (130_2), and the grating height (H1) of the diffraction grating pattern of the first coupler (130_1) may be smaller than the grating height (H2) of the diffraction grating pattern of the second coupler (130_2).

[0139] In this way, the diffraction efficiency of the main laser beam (MLB) may vary depending on the grating width, pitch, and grating height of the diffraction grating pattern of the coupler (130), and the energy intensity of the main laser beam (MLB) provided to the sub laser generator (140) may vary.

[0140] In another embodiment, as illustrated in FIGS. 8, 10 and 11, the shapes of the diffraction grating patterns of each coupler (130) may be different from each other.

[0141] For example, the third coupler (130_3) of FIG. 10 and the fourth coupler (130_4) of FIG. 11 may each have a different diffraction grating pattern shape from the first coupler (130_1) of FIG. 8. The diffraction grating pattern of the third coupler (130_3) may include a first side (131a) and a second side (131b) each including an inclined plane. The diffraction grating pattern of the fourth coupler (130_4) may include a first side (131a) including an inclined plane and a second side (131b) including a vertical plane.

[0142] However, it is not limited to the city on the drawing, and the shape of the diffraction grating pattern of the coupler (130) can be modified in various ways depending on the diffraction efficiency.

[0143] In this way, the diffraction efficiency of the main laser beam (MLB) may vary depending on the shape of the diffraction grating pattern of the coupler (130), and the energy intensity of the main laser beam (MLB) provided to the sub laser generator (140) may vary.

[0144] In another embodiment, as illustrated in FIGS. 8 and 12, the duty cycles of the respective couplers (130) may be different from each other. The duty cycle may be defined as the ratio of the grating width of the diffraction grating pattern to the pitch of the diffraction grating pattern (duty cycle = Width / Pitch).

[0145] For example, the fifth coupler (130_5) of FIG. 12 may have a different duty cycle than the first coupler (130_1) of FIG. 8.

[0146] The duty cycle of the first coupler (130_1) of FIG. 8 may be a ratio of the grating width (W1) of the diffraction grating pattern of the first coupler (130_1) to the pitch (P1) of the diffraction grating pattern of the first coupler (130_1). The first coupler (130_1) of FIG. 8 may have a constant duty cycle for each grating.

[0147] On the other hand, the duty cycle of the fifth coupler (130_5) of FIG. 12 may have two or more different duty cycles.

[0148] For example, the convex portion (131) of the fifth coupler (130_5) may include a first grid (K1), a second grid (K2), and a third grid (K3), and the concave portion (132) of the fifth coupler (130_5) may include a first groove (M1), a second groove (M2), and a third groove (M3). The first grid (K1), the first groove (M1), the second grid (K2), the second groove (M2), the third grid (K3), and the third groove (M3) may be arranged in sequence.

[0149] In one embodiment, the width (W1a) of the first grating (K1) may be greater than the width (W1b) of the second grating (K2), and the width (W1b) of the second grating (K2) may be greater than the width (W1c) of the third grating (K3). The width (D1) of the first groove (M1), the width (D2) of the second groove (M2), and the width (D3) of the third groove (M3) may be equal to each other.

[0150] However, the present invention is not limited thereto, and in other embodiments, the width (D1) of the first groove (M1), the width (D2) of the second groove (M2), and the width (D3) of the third groove (M3) may be different from each other, and the width (W1a) of the first grid (K1), the width (W1b) of the second grid (K2), and the width (W1c) of the third grid (K3) may be the same. In yet other embodiments, the width (D1) of the first groove (M1), the width (D2) of the second groove (M2), and the width (D3) of the third groove (M3) may be different from each other, and the width (W1a) of the first grid (K1), the width (W1b) of the second grid (K2), and the width (W1c) of the third grid (K3) may be different from each other. For convenience of explanation, in the following, as shown in the drawing, an example is given in which the width (W1a) of the first grid (K1), the width (W1b) of the second grid (K2), and the width (W1c) of the third grid (K3) are different, and the width (D1) of the first groove (M1), the width (D2) of the second groove (M2), and the width (D3) of the third groove (M3) are the same.

[0151] The first pitch (P1a) may be the sum of the width (W1a) of the first grid (K1) and the width (D1) of the first groove (M1), the second pitch (P1b) may be the sum of the width (W1b) of the second grid (K2) and the width (D2) of the second groove (M2), and the third pitch (P1c) may be the sum of the width (W1c) of the third grid (K3) and the width (D3) of the third groove (M3).

[0152] The first duty cycle of the fifth coupler (130_5) may be the width (W1a) of the first grating (K1) for the first pitch (P1a) (duty cycle1 = W1a / P1a), the second duty cycle of the fifth coupler (130_5) may be the width (W1b) of the second grating (K2) for the second pitch (P1b) (duty cycle2 = W1b / P1b), and the third duty cycle of the fifth coupler (130_5) may be the width (W1c) of the third grating (K3) for the third pitch (P1c) (duty cycle3 = W1c / P1c). The first to third duty cycles of the fifth coupler (130_5) may be different from each other.

[0153] In this way, the diffraction efficiency of the main laser beam (MLB) may vary depending on the duty cycle of the coupler (130), and the energy intensity of the main laser beam (MLB) provided to the sub laser generator (140) may vary.

[0154] Meanwhile, the fifth coupler (130_5) of FIG. 12 illustrates an example in which multiple duty cycles are included within a single coupler (130), but is not limited thereto. The coupler (130) may include a single duty cycle, like the first coupler (130_1) of FIG. 8. Since the couplers (130) including a single duty cycle have different duty cycles, the energy intensity of the main laser beam (MLB) provided to the sub-laser generator (140) may be adjusted.

[0155] The holographic display (10) according to the present embodiment can apply a main laser beam (MLB) generated from a main laser generator (110) to a sub-laser generator (140) at a desired intensity with the same or different energy level by utilizing the coupling effect, as described with reference to FIGS. 5 to 12. Accordingly, a main laser beam (MLB) of an intensity capable of inducing stimulated emission can be simultaneously applied to each sub-laser generator (140).

[0156] Meanwhile, the holographic display (10) according to the present embodiment can simultaneously apply a main laser beam (MLB) to each sub-laser generator (140), thereby constantly fixing the relative phase difference between the sub-laser beams (SLB) generated from each sub-laser generator (140) for each frame (FRM) (see FIG. 13a) or pulse (PLS) (see FIG. 13b). This will be described later with reference to FIGS. 13a and 13b.

[0157] FIG. 13a and FIG. 13b are timing diagrams showing the driving timing of each of the main laser generator and the sub laser generator according to one embodiment.

[0158] In addition to FIGS. 4 and 5, referring to FIGS. 13a and 13b, the first graph (GR1) is a graph illustrating the laser generation driving timing of the sub laser generator (140), and the second graph (GR2) is a graph illustrating the laser generation driving timing of the main laser generator (110). The x-axis of the first graph (GR1) and the second graph (GR2) represents time. The y-axis of the first graph (GR1) represents the intensity of the laser generation driving current applied to the sub laser generator (140), and the y-axis of the second graph (GR2) represents the intensity of the laser generation driving current applied to the main laser generator (110).

[0159] The amplitude (or intensity) of the sub-laser beam (SLB) generated from the sub-laser generator (140) can be determined according to the intensity of the driving current shown on the y-axis of the first graph (GR1). For example, the greater the intensity (GH) of the driving current shown on the y-axis of the first graph (GR1), the greater the amplitude (or intensity) of the sub-laser beam (SLB).

[0160] The amplitude (or intensity) of the main laser beam (MLB) generated from the main laser generator (110) can be determined according to the intensity of the driving current shown on the y-axis of the second graph (GR2). For example, the greater the intensity of the driving current shown on the y-axis of the second graph (GR2), the greater the amplitude (or intensity) of the main laser beam (MLB).

[0161] In some embodiments, as illustrated in FIG. 13A, the start timing of the application of the driving current applied to the main laser generator (110) may coincide with the start timing of the application of the driving current applied to the sub-laser generator (140) for each frame (FRM). Accordingly, the relative phase difference between the sub-laser beams (SLB) generated from each sub-laser generator (140) may be fixed to be constant for each frame (FRM).

[0162] For example, as described above, each sub-laser generator (140) arranged in each light source pixel (SP) can simultaneously receive a main laser beam (MLB) by the structure of the main laser generator (110), waveguide (120), and coupler (130) of the light source panel (100).

[0163] The sub-laser generator (140) arranged in the light source pixel (SP) shown on the left side of FIG. 4 and the sub-laser generator (140) arranged in the other light source pixel (SP) shown on the right side of FIG. 4 can each emit a sub-laser beam (SLB) by causing stimulated emission by the main laser beam (MLB).

[0164] At this time, as illustrated in FIG. 5, since the light source pixel (SP) and the other light source pixel (SP) are spaced apart from the main laser generator (110) by the same or different distances, the optical path lengths along which the main laser beam (MLB) moves from the main laser generator (110) to the light source pixel (SP) and the other light source pixel (SP) may also be the same or different. When the optical path lengths along which the main laser beam (MLB) moves from the main laser generator (110) to the light source pixel (SP) and the other light source pixel (SP) are different, the phase of the main laser beam (MLB) that reaches the light source pixel (SP) and the phase of the main laser beam (MLB) that reaches the other light source pixel (SP) may be different from each other. That is, the main laser beam (MLB) that reaches the light source pixel (SP) and the main laser beam (MLB) that reaches the other light source pixel (SP) may have a phase difference from each other.

[0165] However, since the optical path length between the main laser generator (110) and the light source pixel (SP) is fixed at a constant rate, and the optical path length between the main laser generator (110) and the other light source pixel (SP) is fixed at a constant rate, the difference in optical path lengths between the light source pixel (SP) and the other light source pixel (SP) can also be fixed at a constant rate. Accordingly, the phase difference between the main laser beam (MLB) reaching the light source pixel (SP) and the main laser beam (MLB) reaching the other light source pixel (SP) can also be fixed at a constant rate.

[0166] In this way, since the relative phase difference between the light source pixels (SP) is fixed according to the relative positions of the light source pixels (SP) and the main laser beam (MLB) reaches the sub-laser generator (140), when the start timing of the application of the driving current applied to the main laser generator (110) matches the start timing of the application of the driving current applied to the sub-laser generator (140), the sub-laser beams (SLB) generated from each of the sub-laser generators (140) can be fixed to have a constant relative phase difference.

[0167] The holographic generation unit (700) (see FIG. 2) reflects the fixed phase difference into a hologram pattern and provides it to the spatial light modulator (300), and the light modulation pixel (MP) of the spatial light modulator (300) modulates the phase of each sub-laser beam (SLB) to generate modulated light (LGT), thereby generating a holographic image (HI) (see FIG. 2).

[0168] In some embodiments, as illustrated in FIG. 13b, the start timing of application of the driving current applied to the main laser generator (110) may be located between the start timing of application of the driving current applied to the sub laser generator (140) in one pulse (PLS) and the end timing of application of the driving current applied to the sub laser generator (140) in the pulse (PLS) preceding the one pulse (PLS).

[0169] For example, in the timing diagram of the driving current applied to the main laser generator (110), the rising edge of the third pulse (PLS) may be located between the rising edge of the first pulse (PLS1) and the falling edge of the second pulse (PLS2) in the timing diagram of the driving current applied to the sub laser generator (140). The second pulse (PLS2) is a pulse of the driving current applied before the first pulse (PLS1). The third pulse (PLS3) is a pulse paired with the first pulse (PLS1). That is, the sub laser beam (SLB) generated by the driving current of the first pulse (PLS1) may be emitted by the main laser beam (MLB) generated by the driving current of the third pulse (PLS3).

[0170] Since the sub-laser generator (140) does not emit a sub-laser beam (SLB) until a driving current is applied, even if the driving current is applied to the main laser generator (110) before the sub-laser generator (140), the sub-laser beams (SLB) generated from each sub-laser generator (140) can be fixed to always have a constant relative phase difference.

[0171] Meanwhile, the amplitude of the sub-laser beam (SLB) generated from the sub-laser generator (140) disposed in the one light source pixel (SP) and the amplitude of the sub-laser beam (SLB) generated from the sub-laser generator (140) disposed in the other light source pixel (SP) can be determined according to the intensity of the driving current applied to each of the sub-laser generators (140) of the one light source pixel (SP) and the other light source pixel (SP).

[0172] Therefore, the holographic display (10) according to the present embodiment can easily modulate the phase of the sub-laser beam (SLB) using fixed phase difference information, and can easily modulate the amplitude of the sub-laser beam (SLB) by adjusting the intensity of the driving current applied to each sub-laser generator (140). In other words, a holographic display capable of complex modulation can be provided.

[0173] Fig. 14 is a plan view showing a spatial light modulator according to one embodiment.

[0174] Referring to FIG. 14, the spatial light modulator (300) may include a display area (DA) and a non-display area (NDA). The display area (DA) may be positioned approximately at the center of the light source panel (100), and the non-display area (NDA) may be positioned to surround the display area (DA).

[0175] The display area (DA) of the spatial light modulator (300) may include a plurality of light modulation pixels (MP), a plurality of light modulation power lines (VL_LM) connected to the plurality of light modulation pixels (MP), a plurality of row-axis light modulation data lines (RL), and a plurality of column-axis light modulation data lines (CL).

[0176] A plurality of optical modulation pixels (MP) may be arranged in a first direction (DR1) and a second direction (DR2). For example, the plurality of optical modulation pixels (MP) may be arranged in a matrix direction. Each of the plurality of optical modulation pixels (MP) may be connected to a plurality of optical modulation power lines (VL_LM), a plurality of row-axis optical modulation data lines (RL), and a plurality of column-axis optical modulation data lines (CL). Each of the plurality of optical modulation pixels (MP) may include at least one transistor, an optical modulation element, and a capacitor. In some embodiments, the capacitor may be omitted.

[0177] The row-axis optical modulation data lines (RL) can extend in a first direction (DR1) and can be spaced apart from each other in a second direction (DR2) intersecting the first direction (DR1). The row-axis optical modulation data lines (RL) can sequentially supply row-axis optical modulation data signals to a plurality of optical modulation pixels (MP).

[0178] The thermal axis optical modulation data lines (CL) can extend in a second direction (DR2) and be spaced apart from each other in a first direction (DR1). The thermal axis optical modulation data lines (CL) can supply thermal axis optical modulation data signals to a plurality of optical modulation pixels (MP).

[0179] The optical modulation power line (VL_LM) can extend in the second direction (DR2) and be spaced apart from each other in the first direction (DR1). The optical modulation power line (VL_LM) can supply a power voltage to a plurality of optical modulation pixels (MP). The power voltage can be at least one of a driving voltage, a high-potential voltage, an initialization voltage, a reference voltage, a bias voltage, and a low-potential voltage.

[0180] The optical modulation timing control unit (310) can receive optical modulation digital data (DATA_LM) and timing signals from the holography generation unit (700). The optical modulation timing control unit (310) can generate a column-axis optical modulation data control signal (CCS) and a row-axis optical modulation data control signal (RCS) based on the timing signals. The optical modulation timing control unit (310) can control the operation timing of the column-axis optical modulation driving unit (320) by supplying the optical modulation digital data (DATA_LM) and the column-axis optical modulation data control signal (CCS) to the column-axis optical modulation driving unit (320). The optical modulation timing control unit (310) can control the operation timing of the row-axis optical modulation driving unit (330) by supplying the optical modulation digital data (DATA_LM) and the row-axis optical modulation data control signal (RCS) to the row-axis optical modulation driving unit (330).

[0181] The column-axis optical modulation driving unit (320) and the row-axis optical modulation driving unit (330) can convert the column-axis optical modulation data control signal (CCS) and the row-axis optical modulation data control signal (RCS) into analog optical modulation data voltages and supply them to the column-axis optical modulation data line (CL) and the row-axis optical modulation data line (RL), respectively.

[0182] The row-axis optical modulation driving unit (330) may be positioned on the left or right side of the non-display area (NDA). The column-axis optical modulation driving unit (320) may be positioned on the upper or lower side of the non-display area (NDA).

[0183] The optical modulation power supply unit (340) can supply power voltage to the spatial light modulator (300), the column-axis optical modulation driving unit (320), and the row-axis optical modulation driving unit (330). The optical modulation power supply unit (340) can generate a driving voltage of the optical modulation element and supply it to a driving voltage line, generate an initialization voltage and supply it to an initialization voltage line, generate a bias voltage and supply it to a bias voltage line, and generate a low-potential voltage and supply it to a low-potential line.

[0184] An optical modulation timing control unit (310), a thermal axis optical modulation driving unit (320), a row axis optical modulation driving unit (330), and an optical modulation power supply unit (340) may be included in the optical modulation driving device.

[0185] A plurality of light modulation pixels (MP) of a spatial light modulator (300) according to the present embodiment can be arranged in a one-to-one correspondence to a plurality of light source pixels (SP) of a light source panel (100). Accordingly, the plurality of light modulation pixels (MP) can individually control the phases of the lights emitted from the plurality of light source pixels (SP).

[0186] The holographic display (10) according to the present embodiment comprises a light modulation driving device including a light modulation timing control unit (310), a thermal axis light modulation driving unit (320), a row axis light modulation driving unit (330), and a light modulation power supply unit (340), thereby independently driving the light source panel (100) and the spatial light modulator (300), thereby implementing a fast response speed.

[0187] Hereinafter, another embodiment of a light source panel according to one embodiment is described. In the following embodiments, the same components as in the previously described embodiments are referred to by the same reference numerals, and redundant descriptions are omitted or simplified, with the differences being primarily described.

[0188] Fig. 15 is a bottom view showing a light source panel according to another embodiment.

[0189] Referring to FIG. 15, the light source panel (100) according to the present embodiment is different from the light source panel (100) according to the embodiment described with reference to FIG. 5, etc., in that some of the sub waveguides (124) are directly connected to the main waveguide (123).

[0190] More specifically, some of the sub-waveguides (124) of the light source panel (100) according to the present embodiment may be directly connected to the main waveguide (123). Some of the sub-waveguides (124) may have a gap size of 0, which is a distance from the main waveguide (123).

[0191] For example, a first gap (G1) having a size greater than 0 may exist between the second main waveguide (123b) and the fourth sub-waveguide (124d), and a second gap (G2) having a size greater than 0 may exist between the second main waveguide (123b) and the fifth sub-waveguide (124e).

[0192] On the other hand, there may be no gap between the second main waveguide (123b) and the sixth sub-waveguide (124f). The second main waveguide (123b) and the sixth sub-waveguide (124f) may be directly connected to each other. In this case, the main laser beam (MLB) that passes through the second main waveguide (123b) and does not move to the fourth sub-waveguide (124d) and the fifth sub-waveguide (124e) may move to the sixth sub-waveguide (124f). The main laser beam (MLB) that moves from the second main waveguide (123b) to the sixth sub-waveguide (124f) may move through total reflection within the waveguide (120) rather than through the coupling effect. In some embodiments, the sub-waveguide (124) that is directly connected to the main waveguide (123) among the sub-waveguides (124) may be placed at the outermost end.

[0193] The holographic display (10) according to the present embodiment can allow the main laser beam (MLB) that was unable to move due to the coupling effect to move completely to the sub waveguide (124) by directly connecting at least some of the sub waveguides (124) to the main waveguide (123). Accordingly, it is possible to prevent energy from accumulating within the waveguide (120) and damaging the waveguide (120).

[0194] Although embodiments of the present invention have been described with reference to the attached drawings, those skilled in the art will appreciate that the present invention can be implemented in other specific forms without altering the technical spirit or essential characteristics of the present invention. Therefore, the embodiments described above should be understood to be illustrative in all respects and not restrictive.

Claims

1. A main laser generator that generates the main laser beam; A plurality of light source pixels, each of which includes a plurality of sub-laser generators that receive the main laser beam and generate sub-laser beams, and A light source panel including a waveguide for transmitting the main laser beam of the main laser generator to the plurality of sub-laser generators; A spatial light modulator disposed on the light source panel and including a plurality of light modulation pixels onto which sub-laser beams generated from the plurality of sub-laser generators are respectively incident; and A holographic display comprising a holographic generation unit configured to provide holographic pattern information to the spatial light modulator.

2. In paragraph 1, The above sub-laser beam is a holographic display that is a coherent light.

3. In paragraph 1, A holographic display in which the main laser beam is incident on the sub-laser generator to induce stimulated emission.

4. In paragraph 1, The above waveguide includes a main waveguide and a sub waveguide, The above main waveguide is connected to the above main laser generator, A holographic display in which one end of the sub-waveguide is positioned adjacent to the main waveguide.

5. In paragraph 4, The above main waveguide provides the main laser beam provided from the main laser generator to the sub waveguide, A holographic display in which the sub-waveguide provides the main laser beam received from the main waveguide to the sub-laser generator.

6. In paragraph 5, A holographic display in which the main waveguide is spaced apart from the sub waveguide.

7. In paragraph 6, A holographic display in which the main waveguide moves the main laser beam located in the main waveguide to the sub waveguide by a coupling effect.

8. In paragraph 7, The coupling effect occurring between the main waveguide and the sub waveguide is a holographic display of direct coupling type.

9. In paragraph 5, The above main waveguide provides the main laser beam to two or more of the above sub waveguides, The two or more sub-waveguides include a first sub-waveguide and a second sub-waveguide, The main waveguide includes a first portion located before passing through the first sub-waveguide and the second sub-waveguide, and a second portion located after passing through the first sub-waveguide and before passing through the second sub-waveguide, A holographic display wherein the energy intensity of the main laser beam within the second portion is less than the energy intensity of the main laser beam within the first portion.

10. In paragraph 9, A holographic display in which the energy intensities of the main laser beam incident on each of the first sub-waveguide and the second sub-waveguide are the same.

11. In paragraph 9, The two or more sub-waveguides further include a third sub-waveguide, The first sub-waveguide and the second sub-waveguide are spaced apart from the main waveguide, The above third sub-waveguide is a holographic display directly connected to the above main waveguide.

12. In paragraph 11, A holographic display in which the first to third sub-waveguides are arranged sequentially along the path of movement of the main laser beam passing through the main waveguide.

13. In paragraph 5, The above sub-waveguide provides the main laser beam to two or more of the above sub-laser generators, The two or more sub-laser generators include a first sub-laser generator and a second sub-laser generator, The sub-waveguide includes a first portion located before passing through the first sub-laser generator and the second sub-laser generator, and a second portion located after passing through the first sub-laser generator and before passing through the second sub-laser generator. A holographic display wherein the energy intensity of the main laser beam within the second portion is less than the energy intensity of the main laser beam within the first portion.

14. In paragraph 13, A holographic display in which the energy intensities of the main laser beams incident on the first sub-laser generator and the second sub-laser generator are the same.

15. In paragraph 4, The above main waveguide includes a first main waveguide and a second main waveguide, The above waveguide, an initial waveguide positioned between the main waveguide and the main laser generator; and Further comprising a splitter positioned between the initial waveguide and the main waveguide, The above splitter splits the main laser beam passing through the initial waveguide, A holographic display in which the divided main laser beam is divided into the first main waveguide and the second main waveguide and moves respectively.

16. In paragraph 1, Further comprising a plurality of couplers arranged adjacent to each of the plurality of sub-laser generators, A holographic display in which the plurality of couplers move the main laser beam located in the waveguide to the plurality of sub-laser generators by a coupling effect.

17. In paragraph 16, The above coupler comprises a diffractive optical element (DOE), A holographic display in which the coupler causes diffraction of the main laser beam located in the waveguide to move the main laser beam to the sub-laser generator.

18. In paragraph 16, The coupling effect occurring between the above coupler and the above sub-laser generator is a holographic display of indirect coupling method.

19. In paragraph 16, The above plurality of couplers include a first coupler and a second coupler, The first coupler and the second coupler include a diffraction grating pattern including a convex portion and a concave portion, A holographic display in which the diffraction grating patterns of the first coupler and the second coupler differ in at least one of grating width, pitch, grating height, and shape.

20. In paragraph 1, The start timing of the laser generation driving current applied to the main laser generator is identical to the start timing of the laser generation driving current applied to the sub laser generator, or A holographic display in which the start timing of application of the laser generation driving current applied to the main laser generator is located between the start timing of application of the laser generation driving current applied to the sub laser generator in one pulse and the end timing of application of the laser generation driving current applied to the sub laser generator in the pulse preceding the one pulse.

21. In paragraph 20, A holographic display in which the relative phase difference between the plurality of sub-laser beams generated from the plurality of sub-laser generators is constant each time the laser generation driving current is applied.

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